#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
float Function(unsigned int n, float x)
{
	if (n == 0)
		return 1;
	else if (n == 1)
		return x;
	else
		return ((2 * n - 1) * x - Function(n - 1, x) - (n - 1) * Function(n - 2, x)) / n;

}



int main()
{
	unsigned int n = 0;
	float x = 0;
	scanf("%u %f", &n, &x);
	printf("%.2f", Function(n, x));

	return 0;
}